docs: def _update_current(self):
          """
          Makes sure that a current is set
          """
          if not self.current or self.current not in self.prefixes:
              if 'default' in self.prefixes:
                  selected_current = 'default'
              elif self.prefixes:
                  selected_current = sorted(self.prefixes.keys()).pop()
              else:
                  # should never get here
                  raise MalformedWorkdir(
                      'No current link and no prefixes in workdir %s' % self.path
                  )
  
              logging.info(
                  'Missing current link, setting it to %s',
                  selected_current,
              )
              self._set_current(selected_current)